This invention relates generally to mass spectrometer controls and more specifically to control of slit mechanisms of adjustable width. The invention may, however, be applied to other areas in which mechanical controls are required to penetrate a vacuum-tight barrier.
In the field of mass spectrometry, the collimator or adjustable slit mechanism is frequently used to limit the size of the ion beam. While several such mechanisms are available in the prior art, as shown in U.S. Pat. No. 2,964,998 by Middlestadt and U.S. Pat. No. 3,171,401 by Powell, all such prior art operates only to narrow or widen the slit dimension and none yields any adjustment for centering the slit position. Such adjustments are left to separate control mechanisms which by their nature, must then require separate vacuum penetrations. Since increasing the number of vacuum penetrations increases the risk of vacuum leaks, it is desirable to minimize such penetrations.
The present invention makes available a simple dual-acting control which both adjusts the slit dimension and moves the entire slit assembly for purposes of alignment with the ion beam. This is accomplished through a single vacuum penetration, thus minimizing the risk of vacuum leaks and highly simplifying vacuum maintenance.